Electrosurgical cutting and sealing instruments with cam-actuated jaws

ABSTRACT

Various embodiments are directed to a surgical instrument comprising, a shaft, and an end effector. The shaft may be coupled to the handle and may extend distally along a longitudinal axis. The end effector may be positioned at a distal end of the shaft and may comprise first and second jaw members and a reciprocating member. The first and second jaw members may define first and second longitudinal slots. One or both of the jaw members may be pivotable relative to the other about a pivot point. The reciprocating member may be translatable distally and proximally parallel to the longitudinal axis and through the first and second longitudinal slots. A distal portion of the reciprocating member may define a blade. The instrument may comprise an overtube translatable distally to exert a force on a portions of the first and second jaw members tending to close the first and second jaw members.

BACKGROUND

Various embodiments are directed to electrosurgical cutting and sealinginstruments with cam-actuated jaws that may be used, for example, inopen and minimally invasive surgical environments.

Minimally invasive procedures are desirable because such procedures canreduce pain and provide relatively quick recovery times as compared toconventional open medical procedures. Many minimally invasive proceduresare performed with an endoscope (including without limitationlaparoscopes). Such procedures permit a physician to position,manipulate, and view medical instruments and accessories inside thepatient through a small access opening in the patient's body.Laparoscopy is a term used to describe such an “endosurgical” approachusing an endoscope (often a rigid laparoscope). In this type ofprocedure, accessory devices (such as end effectors for creatingenergy-induced tissue welds) are inserted into a patient through trocarsplaced through the body wall. Still less invasive treatments includethose that are performed through insertion of an endoscope through anatural body orifice to a treatment region. Examples of this approachinclude, but are not limited to, cystoscopy, hysteroscopy,esophagogastroduodenoscopy, and colonoscopy.

Many of these procedures employ a flexible endoscope during theprocedure. Flexible endoscopes often have a flexible, steerablearticulating section near the distal end that can be controlled by theclinician by utilizing controls at the proximal end. Some flexibleendoscopes are relatively small (1 mm to 3 mm in diameter), and may haveno integral accessory channel (also called biopsy channels or workingchannels). Other flexible endoscopes, including gastroscopes andcolonoscopes, have integral working channels having a diameter of about2.0 to 3.7 mm for the purpose of introducing and removing medicaldevices and other accessory devices to perform diagnosis or therapywithin the patient. For example, some end effectors are used to createan energy-induced weld or seal. Certain specialized endoscopes orsteerable overtubes are available, such as large working channelendoscopes having a working channel of 5 mm, or larger, in diameter,which can be used to pass relatively large accessories, or to providecapability to suction large blood clots. Other specialized endoscopesinclude those having two or more working channels.

A common task both in minimally invasive and open surgical environmentsis to grasp, cut and fasten tissue while leaving the cut ends hemostatic(e.g., not bleeding). For example, it is often desirable to cut and sealbodily lumens, such as individual blood vessels or tissue includingvarious vasculature. When sealing a fluid-carrying bodily lumen, it isoften necessary for the seal to have sufficient strength to preventleakage of the fluid, which may exert considerable fluid pressure.

Instruments exist for simultaneously making a longitudinal incision intissue and fastening the tissue on opposing sides of the incision. Suchinstruments commonly include an end effector having a pair ofcooperating jaw members that, if the instrument is intended forminimally invasive applications, are capable of passing through acannula passageway or endoscopic working channel. In use, the clinicianis able to close the jaw members to clamp the tissue to be cut. Areciprocating cutting instrument (or knife) is drawn distally along thejaw members to transect the clamped tissue. Simultaneously, a fasteningmechanism fastens the cut ends of the tissue on opposing sides of theincision. Known fastening mechanisms include staples, sutures or variousinstruments utilizing energy sources. For example, various energysources such as radio frequency (RF) sources, ultrasound sources andlasers have been developed to coagulate, seal or join together tissuevolumes.

SUMMARY

Various embodiments are directed to a surgical instrument comprising anhandle, a shaft, an end effector, and a reciprocating member. The shaftmay be coupled to the handle and may extend distally along alongitudinal axis. The end effector may be positioned at a distal end ofthe shaft and may comprise first and second jaw members. The first andsecond jaw member may, respectively, define first and secondlongitudinal slots. Further, the second jaw member may be pivotabletowards the first jaw member about a pivot point and comprising a campin positioned offset from the pivot point. The reciprocating member maybe translatable distally and proximally parallel to the longitudinalaxis through the first longitudinal slot and the second longitudinalslot. A distal portion of the reciprocating member may define a blade.The reciprocating member may define a cam slot for receiving the campin. Distal motion of the reciprocating member may exert a force on thecam pin such that the second jaw member pivots towards the first jawmember, and proximal motion of the reciprocating member exerts a forceon the cam pin such that the second jaw member pivots away from thefirst jaw member.

Also, various embodiments are directed to a surgical instrumentcomprising a handle, a shaft, an end effector, a reciprocating memberand an overtube. The shaft may be coupled to the handle and may extenddistally along a longitudinal axis. The end effector may be positionedat a distal end of the shaft and may comprise first and second jawmembers. The first and second jaw member may, respectively, define firstand second longitudinal slots. Further, the first and second jaw membersmay be pivotable relative to one another about a pivot point and maycomprise first and second cam portions positioned proximally from therespective pivot points. The reciprocating member may be translatabledistally and proximally parallel to the longitudinal axis through thefirst longitudinal slot and the second longitudinal slot. A distalportion of the reciprocating member may define a blade. The overtube maybe positioned over the shaft and may be translatable distally toward thepivot point. The overtube may also be configured to contact the firstand second cam portions as it translates distally to apply a force onthe first and second cam portions tending to close the first and secondjaw members.

In addition, various embodiments are directed to a surgical instrumentcomprising a handle, a shaft, a reciprocating member, and an endeffector. The shaft may be coupled to the handle and may extend distallyalong a longitudinal axis. The end effector may be positioned at adistal end of the shaft and may comprise first and second jaw members.The first and second jaw members may, respectively, define first andsecond longitudinal slots. The second jaw member may be pivotablerelative to the first jaw member about the pivot point. Thereciprocating member may comprise an I-beam member translatable distallyand proximally relative to the longitudinal axis through the firstlongitudinal slot and the second longitudinal slot; and a blade membertranslatable distally and proximally separately from the I-beam member.

FIGURES

Various features of the embodiments described herein are set forth withparticularity in the appended claims. The various embodiments, however,may be understood in accordance with the following description taken inconjunction with the accompanying drawings as follows.

FIG. 1 illustrates one embodiment of a transection and sealinginstrument, which may be used, for example, with an endoscope.

FIG. 2 illustrates one embodiment of the transection and sealinginstrument of FIG. 1 for use in electrosurgical applications.

FIGS. 3 and 4 illustrate one embodiment of an end effector of a surgicalgrasping instrument adapted for transecting captured tissue andcontemporaneous sealing of the captured tissue with RF energy delivery.

FIGS. 5 and 6 illustrate one embodiment of the reciprocating membershown in FIGS. 3 and 4.

FIGS. 7 and 8 illustrate one embodiment of the actuation of areciprocating member shown in FIG. 3 from a first retracted position toa second extended position to move the jaws of the end effector from anopen position to a closed position.

FIG. 9 illustrates an end view of one embodiment of the reciprocatingmember of FIG. 3 with the jaws of the end effector in phantom view.

FIG. 10 illustrates a cross-sectional view of the embodiment shown inFIG. 9 along a cross-section taken at a position proximally located fromthe end view shown in FIG. 9.

FIG. 11 illustrates one embodiment of the jaw of the end effector ofFIG. 3 de-mated from the end effector.

FIGS. 12-14 illustrate one embodiment of an end effector having a singlerotating jaw member.

FIGS. 15-18 illustrate another embodiment of an end effector having asingle rotating jaw member.

FIG. 19 illustrates one embodiment of the reciprocating memberconfigured with separate elevated step or cam surfaces in the lowerflange portions that are adapted to slidably engage the ends of therectangular pins on either side of upper jaw.

FIG. 20 illustrates one embodiment of an end effector comprising cam-pinactuated jaw members.

FIG. 21 illustrates one embodiment of the reciprocating member of FIG.20 showing the cam slot.

FIG. 22 illustrates one embodiment of the end effector of FIG. 20 in aclosed position.

FIGS. 23-24 illustrate one embodiment of an end effector having a pairof movable, cam-pin actuated jaw members.

FIGS. 25 and 26 illustrate one embodiment of an end effector comprisingcam-actuated jaw members in an open position.

FIGS. 27 and 28 illustrate one embodiment of the end effector of FIGS.25 and 26 with the jaw members in a closed position.

FIG. 29 illustrates one embodiment of the reciprocating member of FIGS.25-28.

FIG. 30 illustrates one embodiment of the reciprocating member of FIG.29 with a shuttle and cam pin shown.

FIG. 31 illustrates one embodiment of the end effector of FIG. 25 withthe clevis and the shaft shown in FIG. 25 not shown.

FIG. 32 illustrates one embodiment of the end effector as shown in FIG.31 with the clevis also shown.

FIG. 33 illustrates one embodiment of the clevis of the end effector ofFIG. 25.

FIGS. 34 and 35 illustrate one embodiment of the upper jaw member of theend effector of FIG. 25.

FIGS. 36 and 37 illustrate one embodiment of the lower jaw member of theend effector of FIG. 25.

FIGS. 38-40 illustrate one embodiment of an end effector comprising anovertube for providing closing force to jaw members.

FIGS. 41-43 illustrate one embodiment of a reciprocating member that maybe used in any of the end effectors described above in order to allowclosure of jaw members without the advancement of a blade.

FIG. 44 shows an example embodiment of a vessel having opposing wallportions.

FIG. 45 is a graphic illustration of one embodiment of the opposingvessel walls portions of FIG. 44 with the tissue divided into a gridwith arbitrary micron dimensions.

FIG. 46 illustrates one embodiment of the blood vessel of FIG. 44 actedupon by a device implementing a power adjustment approach to energydelivery.

FIG. 47 illustrates one embodiment of the blood vessel of FIG. 44 actedupon by a device implementing a current-path directing approach toenergy delivery.

FIG. 48 illustrates one embodiment of an endoscope (illustrated here asa gastroscope) inserted into the upper gastrointestinal tract of apatient.

FIG. 49 illustrates one embodiment of a distal portion of the endoscopeof FIG. 48, which may be used with the transection and sealinginstrument described herein.

DESCRIPTION

Various embodiments are directed to electrosurgical devices for cuttingand sealing, for example, cutting and sealing a bodily lumen. Accordingto various embodiments, the electrosurgical devices may comprise acam-actuated end effector. The cam-actuated end effector may comprise apair of jaw members and a reciprocating member that may be translatabledistally through the jaw members to provide a clamping force tending toforce the jaw members together and to transect tissue between the jawmembers with a sharpened leading edge. The jaw members may compriseelectrodes and/or another electrically active surface for sealing tissue(e.g., tissue that has been severed). Some embodiments of the endeffectors may be bilateral (both jaw members are pivotable) orunilateral (only one jaw member is pivotable).

According to various embodiments, the reciprocating member may define acam slot configured to receive a cam pin coupled to a movable jawmember. Distal and proximal movement of the reciprocating member maycause the cam pin to translate within the cam slot, which may, in turn,cause the movable jaw member to pivot from an open position (e.g.,proximal position of the reciprocating member) to a closed (e.g., distalposition of the reciprocating member). In embodiments where two jawmembers are movable, both jaw members may comprise a cam pin and thereciprocating member may define a pair of cam slots or grooves. Thecam-actuated nature of the jaw member or members may increase the acuityof the instrument and allow the clinician to increase the force withwhich the jaw members are opened. This may make the surgical instrumentuseful for dissecting as well as for cutting and sealing.

According to various embodiments an end effector may comprise a pair ofmovable jaw members pivotable about a pivot pin or other pivot point.The jaw members may comprise a cam portion proximal of the pivot point.Each cam portion may define a cam slot. A shuttle may comprise one ormore cam pins received within the cam slots. Distal and proximalmovement of the shuttle may cause the cam pin or pins to slide withinthe respective cam slots of the jaw members. This may, in turn, causethe jaw members to open and close. In some embodiments, an overtube maybe provided. The overtube may extend distally and contact the camportions of the jaw members, forcing them towards a longitudinal axis ofthe end effector.

According to various embodiments, the reciprocating member of any of theend effectors described above may comprise an I-beam member and a blademember. The I-beam member may define a slot for receiving the blademember such that the blade member may translate distally and proximallyrelative to the I-beam member. In use, the I-beam member may betranslated distally separately from the blade member. In this way, theI-beam member may act to close the jaw members, and/or to provide aclamping force tending to force the jaw members together without theblade member extending to transect tissue or material present betweenthe jaw members. The blade member may then be separately extended totransect the tissue or material. In this way, the end effector may beused for grasping as well as for cutting and sealing.

FIG. 1 illustrates one embodiment of a transection and sealinginstrument 100. The instrument 100 may be used with an endoscope,laparoscope, or any other suitable introduction device. According tovarious embodiments, the transection and sealing instrument 100 maycomprise a handle assembly 102, a shaft 104 and an end effector 106. Theshaft 104 may be rigid (e.g., for laparoscopic application and/or opensurgical application) or flexible, as shown, (e.g., for endoscopicapplication). In various embodiments, the shaft 104 may comprise one ormore articulation points (e.g., in embodiments where the shaft 104 isrigid). The end effector 106 may comprise a first jaw member 108 and asecond jaw member 110. The first jaw member 108 and second jaw member110 may be connected to a clevis 112, which, in turn, may be coupled tothe shaft 104. In various embodiments, as illustrated below, the jawmembers 108, 110 may be directly coupled to the shaft 104 and the clevis112 may be omitted. As illustrated in FIG. 1, the end effector 106 isshown with the jaw members 108, 110 in an open position. A reciprocatingblade/I-beam member 340 is illustrated between the jaw members 108, 110.

According to various embodiments, one or both of the jaw members 108,110 may include, or serve as electrodes in monopolar or bi-polarelectrosurgical applications including, for example, cutting,coagulation and welding. FIG. 2 illustrates one embodiment of thetransection and sealing instrument 100 for use in electrosurgicalapplications. The jaw members 108, 110 of the end effector 106 maycomprise respective electrodes 120, 122. The electrodes 120, 122 may beconnected to an electrosurgical generator 124 via wires (not shown)extending from the end effector 106 through the shaft 104 and handle102. The generator 124 may generate any suitable type of signal forelectrosurgical applications. For example, the generator 124 may makevarious alternating current (A/C) and/or direct current (D/C) signals atsuitable voltages, currents, frequencies and wave patterns. According tovarious embodiments, the transection and sealing instrument 100 may beconfigured for monopolar operation. In this case, the end effector 106may comprise a single electrode, rather than two. According to variousembodiments, all or a portion of the end effector 106 may serve as thesingle electrode.

A translating member 116 may extend within the shaft 104 from the endeffector 106 to the handle 102. The translating member 116 may be madefrom any suitable material. For example, the translating member 116 maybe, a metal wire (e.g., a tri-layered steel cable), a plastic or metalshaft, etc. In some embodiments, one or more additional translatingmembers (not shown in FIG. 2) may be included to control the motion ofthe end effector 106 and/or the shaft 104. In various embodiments, theinstrument 100 may comprise multiple translating members 116, forexample, as described below. At the handle 102, the shaft 104 may bedirectly or indirectly coupled to an actuator 113 (FIG. 1). In use, aclinician may cause the actuator 113 to pivot along arrow 118 from afirst position to a second position. When the actuator moves from thefirst position to the second position, it may translate the translatingmember 116 distally or proximally. Distal or proximal motion of thetranslating member 116 may, in turn, cause the end effector 106 totransition from an open position to a closed position (or vice versa)and/or to perform various other surgical activities such as, forexample, severing and/or joining or welding. According to variousembodiments, the handle 102 may comprise multiple actuators 113. Whenmultiple actuators 113 are present, each actuator 113 may be used by aclinician to cause the end effector 106 to perform different surgicalactivities. In various embodiments a single actuator 113 may cause theend effector 106 to perform more than one activity. For example, aclinician may activate a single actuator 113 to force a reciprocatingmember 340 distally. This may, as described, both close the jaw members108, 110 and transect any tissue between the jaw members 108, 110.

FIGS. 3 and 4 illustrate one embodiment of an end effector 106 of theinstrument 100 adapted for transecting captured tissue andcontemporaneous sealing of the captured tissue with RF energy delivery.The end effector 106 is carried at the distal end 304 of the shaft 104that can be rigid, articulatable or deflectable in any suitablediameter. For example, the shaft 104 can have a diameter ranging fromabout 2 mm to 20 mm to cooperate with cannulae inendoscopic/laparoscopic surgeries or for use in open surgicalprocedures. The shaft 104 extends from a proximal handle, such as thehandle 102. The handle 102 can be any type of pistol-grip or other typeof handle known in the art that carries actuator levers, triggers orsliders for moving the translating member 116 or members distally andproximally to actuate the jaws as will be disclosed below. The shaft 104has a bore 308 extending therethrough for carrying actuator mechanisms(e.g., translating member 116) for actuating the jaws and for carryingelectrical leads 309 a-309 b for the electrosurgical components of theend effector 106.

FIGS. 3 and 4 show details of the end effector 106, including the(upper) jaw element 108 and (lower) jaw element 110 that are adapted toclose or approximate along an axis 315. The jaw elements 108, 110 mayboth be moveable or a single jaw may rotate to provide the open andclosed positions. In the example embodiment of FIGS. 1 and 2, both thelower and upper jaws 110, 108 are moveable relative to a rolling pivotlocation 316 defined further below.

An opening-closing mechanism of the end effector 106 operates on thebasis of cam mechanisms that provide a positive engagement of cammingsurfaces both distal and proximal to a pivoting location (i) for movingthe jaw assembly to the (second) closed position to engage tissue undervery high compressive forces, and (ii) for moving the jaws toward the(first) open position to apply substantially high opening forces for“dissecting” tissue. This feature allows the surgeon to insert the tipof the closed jaws into a dissectable tissue plane—and thereafter openthe jaws to apply such dissecting forces against the tissues.

According to various embodiments, the lower and upper jaws 110, 108 mayhave a first end 318, in the open position, that defines first(proximally-facing) arcuate outer surface portions indicated at 320 aand 320 b that are engaged by a first surface portions 322 a and 322 bof a reciprocating I-beam member 340 (FIG. 4) that is adapted to slideover the jaw elements 108, 110 to thereby move the jaws toward closedposition. FIGS. 5 and 6 show views that illustrate the cam surfaces ofreciprocating member 340 de-mated from jaws 110 and 108. The first endportion 318 of the lower and upper jaws, in the open position, furtherdefines second (distally-facing) arcuate surface portions indicated at330 a and 330 b that are engaged by second surface portions 332 a and332 b (FIG. 5) of the reciprocating member 340 for moving the jawelements to the open position. The effective point of jaw rotation maylie between the first and second arcuate cam surfaces of the jaws. Thedistal (second) end region 333 of the paired jaws is rounded with a lip334 that can serve as an electrode for surface coagulation as will bedescribed below.

In this embodiment of FIGS. 3, 4 and 5, the reciprocating member 340 maybe actuatable from the handle of the instrument by any suitablemechanism, such as actuator 113. For example, the actuator 113 may becoupled to a proximal end 341 of the member 340 and/or may be coupled toa translating member or members 116 that are, in turn, coupled to thereciprocating member. The proximal end 341 and medial portion 341′ ofmember 340 are dimensioned to reciprocate within bore 308 of the shaft104. The distal portion 342 of reciprocating member 340 carries first(lower) and second (upper) laterally-extending flanges or shoulderelements 344A and 344B that are coupled by an intermediate transverseelement 345. The transverse element 345 further is adapted to transecttissue captured between the jaws with a leading edge 346 (FIG. 5) thatcan be a blade or a cutting electrode. The transverse element 345 isadapted to slide within channels 348 a and 348 b in the paired first andsecond jaws 110, 108. As can be seen best in FIGS. 5 and 6, thelaterally-extending shoulder elements 344A and 344B define the surfaces322 a, 322 b, 332 a, 332 b that slidably engage the arcuate cam surfacesof the jaws and that apply high compressive forces to the jaws in theclosed position.

According to various embodiments, the first and second jaws 108 and 110may define tissue-engaging surfaces or planes 350 a and 350 b thatcontact and deliver energy to engaged tissues, in part, from RFelectrodes 120, 122. The engagement plane 350 a of the lower jaw 110 maybe adapted to deliver energy to tissue, and the tissue-contactingsurface 350 b of upper jaw 108 may be electrosurgically active orpassive as will be described below. Alternatively, the engagementsurfaces 350 a, 350 b of the jaws can carry any suitable electrodearrangement known in the art.

The jaws 108, 110 may have teeth or serrations 356 in any location forgripping tissue. The embodiment of FIGS. 3 and 4 depicts such serrations356 at an inner portion of the jaws along channels 348 a and 348 b thusleaving engagement planes 350 a and 350 b laterally outward of thetissue-gripping elements. The serrations 356 may be of any suitablesymmetric or asymmetric shape or combination of shapes including, forexample, triangular, rounded, sinusoidal, etc. In the embodimentsdescribed below, the engagement planes 350 a and 350 b and electrode(s)120, 122 generally are shown with a non-serrated surface for clarity ofexplanation, but such engagement planes and electrodes themselves can beany non-smooth gripping surface. The axial length of jaws 108, 110indicated at L can be any suitable length depending on the anatomicstructure targeted for transection and sealing. In various embodiments,the length L may be between 10 mm and 50 mm. In some embodiments, thelength L may be longer. For example, one embodiment of an end effector106 for resecting and sealing organs such as a lung or liver may have alength L of about 200 mm. Also, for example, for some surgical tasks,the jaws having a shorter length L may be used, including, for example,jaws having a length L of about 5.0 mm.

FIG. 9 illustrates an end view of one embodiment of the reciprocatingmember 340 with the jaws 110 and 108 in phantom view. The view shown inFIG. 9 is a head-on view with the distally positioned blade surface 346pointed out of the page. FIG. 10 illustrates a cross-sectional view ofthe embodiment shown in FIG. 9 along a cross-section taken at a positionproximally located from the end view shown in FIG. 9. The transverseelement 345 of the reciprocating member 340 may define a transversedimension d between innermost surfaces 358 a and 358 b of the flanges344A, 344B of the reciprocating member 340 and cooperating medial anddistal outer surfaces 360A and 360B of the jaws. The selected transversedimension d between the flanges or shoulders 344A and 344B thus furtherdefines the engagement gap g between the engagement planes 350 a and 350b of the jaws in the closed position. It has been found that very highcompression of tissue combined with controlled RF energy delivery isoptimal for welding the engaged tissue volume contemporaneous withtransection of the tissue. According to various embodiments, theengagement gap g between the engagement planes 350 a, 350 b may rangefrom about 0.001″ to about 0.050″. For example, the gap g between theengagement planes ranges from about 0.001″ to about 0.010″. As can beseen in FIGS. 5 and 10, the medial portion 341′ of the reciprocatingmember 340 may have an “I”-beam shape with inner surface portions 363 aand 363 b that engage the cooperating medial outer surfaces of the jaws.Thus, in various embodiments, the entire length L of the jaws can bemaintained in a fixed spaced-apart relationship to define a consistentengagement gap g. According to various embodiments, the engagement gap gmay be selected to be large enough to prevent tissue engaged between thejaws 108, 110 from being sheared and to prevent electrical shortsbetween the electrodes 120, 122.

FIGS. 7 and 8 illustrate one embodiment of the actuation of thereciprocating member 340 from a first retracted position to a secondextended position to move the jaws 110 and 108 from an open position toa closed position. Referring to FIG. 7, it can be seen that thetranslatable member 340 is being moved in the proximal direction so thatthe proximal-facing surfaces 332 a and 332 b (FIG. 5) of reciprocatingmember 340 about the outer surfaces 330 a and 330 b of the jaws thusforcing the jaws apart, for example to apply dissecting forces totissues or to open jaws 108 and 110 to engage targeted tissues forhemostasis and transection. FIG. 8 shows the reciprocating member 340after having been fully extended in the distal direction so that thedistal-facing surfaces 322 a and 322 b of reciprocating member 340 haveridden up and over the proximal arcuate surfaces 320 a and 320 b of thejaws (and medial outer surfaces 360A and 360B) thus forcing the jawstogether thereby producing a compressive force between jaws 108 and 110.According to various embodiments, the orientation of surfaces 322 a, 322b of the reciprocating member 340 and/or the arcuate surfaces 320 a, 320b may be modified to modify the compression rate provided by thereciprocating member 340. For example, the orientation of the 322 a, 322b of the reciprocating member 340 and/or the arcuate surfaces 320 a, 320b may vary from one embodiment to another, or may vary within a singleembodiment in order to cause variable compression rates within a singlestroke of the reciprocating member 340.

According to various embodiments, the jaws 108, 110 may rollably contactone another along the interface 370 between inner surfaces 372 of thefirst end 318 of the jaws. As jaws 108 and 110 articulate, the pivotpoint is moving as the point of contact changes at the interface betweensurfaces 370 and 372. Thus, the jaw assembly may not need to define atrue single pivot point as is typical of hinge-type jaws known in theart. The pivotable action of the jaws along interface 370 may bedescribed as a rolling pivot that optionally can allow for a degree ofdynamic adjustment of the engagement gap g at the proximal end of thejaws. FIG. 11 illustrates one embodiment of the jaw 108 de-mated fromthe end effector 106. Referencing FIG. 11, the jaws elements 110, 108can be retained relative to one another and the shaft 104 by means ofprotruding elements 375 that couples with arcuate slots 376 in aninternal member 377 that is fixedly carried in bore 308 of shaft 104.Alternatively, outwardly protruding elements can cooperate with slots inthe wall of shaft 104. Also, for example, the jaw assembly may(optionally) comprise springs for urging the jaws toward the openposition, or closed position depending on the desired at-rest state ofthe device.

FIGS. 12-13 illustrate one embodiment of an end effector 1200 having asingle rotating jaw member. Like the end effector 106 described above,the end effector 1200 is carried at the distal end 304 of the shaft 104that has a bore 308 extending therethrough. According to variousembodiments, the first (lower) jaw 1210 may be a fixed extension portionof the shaft 104. As can be seen in FIGS. 12 and 13, the second (upper)jaw 1208 is adapted to close or approximate along longitudinal axis1215.

The opening-closing mechanism of end effector 1200 may provide camsurfaces for positive engagement between reciprocating member 340 andthe jaws (i) for moving the jaws to a closed position to engage tissueunder high compressive forces, and (ii) for moving the jaws toward the(first) open position thereby providing high opening forces to dissecttissue with outer surfaces of the jaw tips. The reciprocating member 340operates as described previously to reciprocate within bore 308 of theshaft 104. As can be seen in FIG. 13, the distal end portion 342 ofreciprocating member 340 carries distal first and secondlaterally-extending flange portions 344A and 344B with theblade-carrying transverse element 345 extending therebetween. Theblade-carrying member slides within channels 348 a and 348 b in thejaws.

In the example embodiment of FIGS. 12 and 13, the first and second jawmembers 1210 and 1208 again define engagement surfaces or planes 1250 aand 1250 b that deliver energy to engaged tissue. The engagement planesmay carry one or more conductor/electrodes 1255 and, in variousembodiments, may comprise a PTC matrix 1285 in at least one of the jaws'engagement surfaces 1250 a and 1250 b. In the embodiment of FIGS. 12 and13, the upper jaw 1208 has a proximate end region 1258 that, in the openposition, defines a first (proximally-facing) arcuate cam surfaceindicated at 1260 that is engaged by a first surface portion 1562 of thereciprocating member 340. The first (proximal) end region 1258 of theupper jaw, in the open position, further defines second(distally-facing) surface portions indicated at 1270 a and 1270 a′ thatare engaged by second surface 1272 of reciprocating member 340 formoving the jaw assembly to an open position.

As can be seen best in FIG. 13, the cam surfaces 1270 a and 1270 a′ maybe formed into pins or projecting elements 1274 and 1274′ that may servemultiple purposes. Referring to FIG. 14, the pins 1274 and 1274′ extendthrough the upper jaw body 1276 b and are received within arcuate bores1277 in body 1276 a of lower jaw 1210. The lower portions 1278(collectively) of the pins 1274 and 1274′ thus can retain upper jaw 1208and prevent it from moving axially or laterally relative to the jaw axis1215 while still allowing the jaw's rotation for opening and closing.The pin mechanism further allows for greatly simplified assembly of theinstrument.

The pins 1274 and 1274′ may provide additional functionality byproviding a degree of “vertical” freedom of movement within the first(proximal) end portion 1258 of the jaw. As can be seen in FIGS. 12 and19, the distal laterally-extending flange portions 344A and 344B definea transverse dimension d (cf. FIG. 19) that in turn determines thedimension of the engagement gap g of the distal end of the jaws in thejaw-closed position (FIG. 14). The transverse dimension d equals thedimension between inner surfaces of flange portions 344A and 344B thatslidably contact the outer surfaces of both jaws.

FIGS. 15-18 illustrate another embodiment of an end effector 1500 thatprovides both electrosurgical functionality and improved grasping anddissecting functionality for endoscopic surgeries. In FIGS. 15-18, boththe upper and lower jaws are shown in cut-away views to show internalcam surfaces of the upper jaw 1510 and the reciprocating member 340. Thejaw assembly 1500 may carry engagement surfaces for applyingelectrosurgical energy to tissue as in the previously describedembodiments, as well as cutting means for transecting the engaged tissuevolume. The jaw assembly 1500 relates to the ability of the jawstructure, in one mode of operation, to be used for general grasping anddissecting purposes wherein the distalmost tips 1513 of the jaws canclose tightly on tissue with little movement of the actuator lever 113in the handle of the instrument. At the same time, in another mode ofoperation, the jaw assembly 1500 can close to apply very highcompressive forces on the tissue to enable welding. Thus, the jawstructure may provide (i) a first non-parallel jaw-closed position forgrasping tissue with the distal jaws tips (FIG. 17), and (ii) a secondparallel jaw-closed position for high compression of tissue for theapplication of electrosurgical energy (FIG. 18).

Referring to FIG. 15, the end effector 1500 again has a shaft 104 thatis similar to the shaft 104 as used by the end effector 1200 with first(lower) jaw 1510 comprising a fixed extending portion 1514 of the shaft104. As can be seen in FIG. 15, the second (upper) jaw 1508 is adaptedto close or approximate about longitudinal axis 1515. Theopening-closing mechanism of jaw assembly 1500 provides cam elements andcooperating jaw surfaces for positive engagement between thereciprocating member 340 as described previously (i) for moving the jawsto a closed position to engage tissue, and (ii) for moving the jawstoward the open position thereby providing high opening forces todissect tissue with outer surfaces of the jaw tips 313.

The reciprocating member 340 (FIG. 19) operates as described previouslyto reciprocate within bore 308 of the shaft 104 (FIG. 15). As can beseen in FIG. 15, the distal end 342 of the reciprocating member 340again carries distal flange portions 344A and 344B with a blade-carryingtransverse portion 345 therebetween. The transverse portion 345 slideswithin channels 348 a and 348 b in the paired jaws. In the exampleembodiment of FIG. 15, the first and second jaws 1510 and 1508 againdefine engagement surfaces 1550 a and 1550 b that can deliverelectrosurgical energy to engaged tissue.

In the embodiment of FIG. 15, the upper jaw 1508 has a proximal end 1558that defines a first (proximally-facing) arcuate jaw surface 1560 thatis engaged by a first cam surface element 1562 of reciprocating member340 for opening the jaw. The proximal end 1558 of the upper jaw furtherdefines second (distally-facing) jaw surface portions indicated at 1570a and 1570 a′ that are engaged by second cam element 1572 ofreciprocating member 340 for moving the jaw assembly to an openposition.

The embodiment of FIG. 15 shows that the upper jaw 1508 has a floatingprimary pivot location indicated at P₁ that is provided by theprojecting elements or rectangular pins 1574 (collectively) on eitherside of the channel portions 348 a that slidably extend into bores 1577(collectively) in the lower jaw body (cf. Figure Z3). The lower portionsof the pins 1574 thus allow upper jaw 1508 to rotate while at the sametime the pin-and-bore mechanism allows the upper jaw to move upwardlyaway from the lower jaw.

For example, the degree of “vertical” freedom of movement of the upperjaw allows for the system to “tilt” the distal tip 1513 of upper jaw1508 toward the axis 1515 to thereby allow the distal jaw tips 1513 tograsp tissue. This is termed a non-parallel closed position herein. Thetilting of the jaw is accomplished by providing a plurality of camsurfaces in the upper jaw 1508 and the reciprocating member 340.

As can be seen in FIGS. 15 and 19, the lower and upperlaterally-extending flange portions 344A and 344B of the reciprocatingmember 340 define a transverse dimension d that determines the dimensionof gap g between the engagement surface of the jaws in the fullyjaw-closed position (FIG. 18). The transverse dimension d equals thedimension between inner surfaces of flange portions 344A and 344B thatslidably contact the outer surfaces of both jaws.

FIG. 19 illustrates one embodiment of the reciprocating member 340configured with separate elevated step or cam surfaces 1590 in the lowerflange portions 344A that are adapted to slidably engage the ends 1595of the rectangular pins 1574 on either side of upper jaw 1508. Theelevated cam surfaces 1590 of reciprocating member 340 thus createanother transverse dimension d′ between inner surfaces of the flangeportions 344A and 344B that move the jaws toward either the firstjaw-closed position or the second jaw-closed position.

Now turning to FIGS. 15-18, the sequence of cut-away views illustratehow the multiple cam surfaces cause the jaws to move between a first“tilted” jaw-closed position to a second “high-compression” jaw-closedposition. In FIG. 15, the jaws are in an open position. In FIG. 16, thereciprocating member 340 is moved distally and its cam surface element1562 pushes on jaw surfaces 1560 to move the jaws toward a closedposition wherein the jaws rotate about primary pivot location P₁. InFIG. 16, it can be seen that the elevated cam surfaces 1590 in the lowerflange 344A have not yet engaged the ends 1595 of the rectangular pins1574.

Now turning to FIG. 17, the reciprocating member 340 is moved furtherdistally wherein the elevated cam surfaces 1590 of lower flange 344Ahave now engaged and elevated the ends 1595 of rectangular pins 1574thereby tilting the upper jaw. The upper jaw 1508 is tilted slightly byforces in the direction of the arrows in FIG. 17 as the upper flange1544B holds the upper jaw 1508 at a secondary pivoting locationindicated at P₂—at the same time that the step of the cam surfaceelement 1590 lifts the pins 1574 and the proximal portion 1558 of theupper jaw 1508 upward.

Thus, the system functions by providing a slidable cam mechanism forlifting the proximal end of the jaw while maintaining the medial jawportion in a fixed position to thereby tilt the distal jaw to the secondjaw-closed position, with the pivot occurring generally about secondarypivot P₂ which is distal from the primary pivot location P₁.

FIG. 18 next shows the reciprocating member 340 moved further distallywherein the elevated cam surfaces 1590 of lower flange 344A slidesdistally beyond the ends 1595 of rectangular pins 1574 thus causing theflanges 344A and 344B together with the trailing edge portions 1575 ofthe “I”-beam portion (FIG. 19) of the member 340 to apply very highcompression forces over the entire length of the jaws as indicated bythe arrows in FIG. 18. This position is termed a parallel jaw-closedposition herein. Another advantage is that the jaw structure is in a“locked” position when the reciprocating member 340 is fully advanced.

FIG. 20 illustrates one embodiment of an end effector 2000 comprisingcam-pin actuated jaw members 2008, 2010. Tissue 2020 is shown betweenthe members 2008, 2010. The end effector 2000 may provide increasedopening force allowing it to be used in more dissecting applications. Byincreasing the functions that may be performed by the end effector 2000,the number of instrument changes during a procedure may be minimized.The upper rotating jaw member 2008 may pivot relative to the lower jawmember 2010 about a rolling pivot P₂. As illustrated, the jaw member2008 may comprise a cam pin 2002 which extends through a cam slot 2004defined by the reciprocating member 340′. The cam pin 2002 may be offsetfrom the pivot point such that motion of the cam pin 2002 may tend tocause motion of the jaw member 2008. FIG. 21 illustrates one embodimentof the reciprocating member 340′ showing the cam slot 2004. FIG. 22illustrates one embodiment of the end effector 2000 in a closedposition.

The cam slot 2004 may have a distal portion 2016, a transition portion2014 and a proximal portion 2012 (Figure A2). The distal portion 2016may be positioned low in the member 340′ such that when the cam pin 2002rides within the distal portion 2016 of the cam slot 2004, the jawmember 2008 may pivot about the pivot P₂ to the open position shown inFIG. 20. To close the jaw members 2008, 2010, the reciprocating member340′ may be pushed distally. As described above, transverse member 345of the reciprocating member 340′ may slide within respective slots 2038a, 2038 b in the jaw members 2008, 2010. Flange portions 344B of thereciprocating member 340′ may contact the jaw member 2008, forcing it tothe closed position as described herein. Additionally, as the member340′ moves distally, the cam pin 2002 of the jaw 2008 may be pushedthrough the distal portion 2016 of the cam slot 2004, through thetransition portion 2014 and into the proximal portion 2012. This mayraise the portion of the jaw member 2008 including the cam pin 2002relative to the pivot P₂, causing the jaw member 2008 to transition tothe closed position shown in FIG. 22. Once the jaw member is in theclosed position shown in FIG. 22, the member 340′ may be pushed furtherin the distal direction to hold the jaw members 2008, 2010 togetherand/or to cause the distal edge 346 of the member 340′ to transecttissue 2020.

Retracting the member 340′ in the proximal position may cause the campin 2002 to translate from the proximal portion 2012, through thetransition portion 2014 to the distal portion 2016. The process mayserve to force the jaw member 2008 to the open position shown in FIG.20. This opening process may be utilized by clinicians to transecttissue, dissect tissue and/or insert targeted tissues into the jawsduring surgery during surgery. According to various embodiments, the campin embodiments described herein may provide superior opening force,allowing the clinician to use the end effector 2000 for dissection tasksthat previously required a separate instrument.

The cam pin concept shown in FIGS. 20-22 may also be used in embodimentshaving two movable jaw members. For example, FIGS. 23-24 illustrate oneembodiment of an end effector 2300 having a pair of movable, cam-pinactuated jaw members 2308, 2310. The jaw members 2308, 2310 may bepivotable about a pivot pin 2302. The pin 2302 may be coupled to theshaft 104, as shown, or may be coupled to a clevis (not shown in FIG.23), for example, as illustrated by clevis 112 shown in FIG. 1 above.The jaw members 2308, 2310 may comprise respective cam portions 2307,2305. The cam portions 2307, 2305 may, in turn, comprise respective campins 2304, 2306. The cam pins 2304, 2306 may ride within a pair of camslots 2312, 2314 of a reciprocating member 340″. According to variousembodiments, the cam slots 2312, 2314 may not extend all the way throughthe member 340″ (e.g., the cam slots 2312 may thought of as camgrooves). This may prevent the respective pins 2304, 2306 frominterfering with one another.

Each of the cam slots 2314, 2312 may comprise distal portions 2320,2346, transition portions 2318, 2344, and proximal portions 2316, 2322.When the member 340″ is pulled proximally, as shown in FIG. 23, the jawmembers 2308, 2310 may be in the illustrated open position and the campins 2304, 2306 may rest in the distal portions 2320, 2346 of therespective cam slots 2312, 2314. To close the jaws, the reciprocatingmember 340″may be pushed distally, as shown in FIG. 24. This may causethe cam pins 2304, 2306 to slide from the distal portions 2320, 2346through the transition portions 2318, 2344 to the proximal portions2316, 2322 of the cam slots 2312, 2314. This may, as shown, cause thejaw members 2308, 2310 to pivot about the pivot pin 2302 to the closedposition shown in FIG. 24. To open the jaw members 2308, 2310, thereciprocating member 340″ may be pulled distally to the position shownin FIG. 23. This may cause the cam pins 2304, 2306 to transition back tothe distal portions 2320, 2346 of the cam slots 2312, 2316 which, inturn, may force the jaw members 2308, 2310 to the open position.

FIGS. 25 and 26 illustrate one embodiment of an end effector 2500comprising cam-actuated jaw members 2502, 2504 in an open position. Thejaw members 2502, 2504 may be pivotably coupled to a clevis 2514 at apivot point 2516 such that the jaw members 2502, 2504 may transitionfrom the open position shown in FIGS. 25 and 26 to the closed positionshown in FIGS. 27 and 28 and described below. As shown in FIGS. 25-28,both jaw members 2502, 2504 may be pivotable about the pivot point 2516.In some embodiments, however, one of the jaw members may be stationary.The pivot point 2516 may be any suitable kind of joint and, in variousembodiments, may comprise a pin. The jaw members 2502, 2504 may comprisetissue-engaging surfaces or planes 2536 a, 2536 b that may be similar tothe tissue engaging planes 350 a, 350 b described above and may be, orcomprise, one or more electrodes for delivering energy to tissue heldbetween the jaw members 2502, 2504, as described herein. Wire conduits2542, 2544, 2546 may be present, as shown, to carry wires from theelectrodes to the generator 324, e.g., via the shaft 104.

Each of the jaw members 2502, 2504 may comprise respective cam portions2506, 2508 positioned substantially or entirely proximally from thepivot point 2516. The cam portions 2506, 2508 may define cam slots 2510,2512. A shuttle 2520 may be coupled to the cam portions 2506, 2508 via acam pin 2518 received through both of the cam slots 2510, 2512.According to various embodiments, the cam pin 2518 may comprise two campins on opposite sides of the shuttle 2520. Also, according to variousembodiments, the drive pin 2518 or pins may not extend all the waythrough the cam slots 2510, 2512.

The cam slots 2510, 2512 may be curved such that distal motion of theshuttle 2520 may cause the jaw members 2502, 2504 to pivot about thepivot point 2516 to the open position shown in FIG. 25. Similarly,proximal motion of the shuttle 2520 may cause the jaw members 2502, 2504to pivot about the pivot point 2516 to a closed position, for example,as shown in FIGS. 27 and 28. Distal and proximal motion of the shuttle2520 may be effected by a translating member 2530 (FIG. 30), which mayextend proximally to the handle 102. At the handle 102, an actuator,such as actuator 113 may be coupled to the translating member 2530 suchthat a clinician may move the actuator 113 in order to cause distal andproximal motion of the translating member 2530. Distal and proximalmotion of the translating member 2530 may cause similar distal andproximal motion of the shuttle 2520, which may, in turn cause the jaws2502, 2504 to open and close.

The end effector 2500 may also comprise a reciprocating I-beam member2524 similar to the member 340 described above. FIG. 29 illustrates oneembodiment of the reciprocating member 2524. The member 2524 maycomprise a transverse element 2532 and a pair of flanges 2528 a, 2528 b.The transverse element 2532 may comprise a distally directed leadingedge or blade 2526, which may be sharpened or be electrically active tocut tissue. When the jaw members 2502, 2504 are in the closed positionshown in FIGS. 27 and 28, the transverse element may be translateddistally to cut tissue held between the jaw members 2502, 2504 and, invarious embodiments, to provide a compressive force tending to hold thejaw members 2502, 2504 together. For example, the transverse element2532 of the reciprocating member 2524 may be adapted to slide withinslots 2534 a, 2534 b in the jaw members 2502, 2504. Flanges 2528 a, 2528b may ride above the slots 2534 a, 2534 b. As the reciprocating member2524 is translated distally through the slots 2534 a, 2534 b, theflanges 2528 a, 2528 b may exert a compressive force on the jaw members2502, 2504, tending to force the jaw members 2502, 2504 together. Thereciprocating member 2524 may be actuatable from the handle 102 of theinstrument by any suitable mechanism, such as actuator 113, which may becoupled to a proximal end of member 2524. The proximal end and medialportion of member 340 may be dimensioned to reciprocate within bore 308of the shaft 104.

According to various embodiments, the reciprocating member 2524 and theshuttle 2520 may be configured to translate distally and proximallysubstantially independent of one another. For example, the reciprocatingmember 2524 may define a slot 2536 in the transverse member 2532 forreceiving the shuttle 2520 and the cam pin 2518. FIG. 30 illustrates oneembodiment of the reciprocating member 2524 with the shuttle 2520 andcam pin 2518 shown. The shuttle 2520 and cam pin 2518 may be movabletransversely and distally relative to the reciprocating member 2524(e.g., as shown by arrow 2538). In this way, the reciprocating member2524 may have a range of motion along the arrow 2538 while the shuttle2520 is stationary. Likewise, the shuttle 2520 may have a range ofmotion along the arrow 2538 while the reciprocating member 2524 remainsstationary.

FIG. 31 illustrates one embodiment of the end effector 2500 with theclevis 2514 and the shaft 104 shown in FIG. 25 omitted. The cam pin 2518is shown riding within the slot 2536 in the reciprocating member 2524 aswell as within the slot 2510 of the cam portion 2506 of the jaw member2502. A coupling 2540 for fastening the clevis 2514 to the shaft 104 isalso illustrated. FIG. 32 illustrates one embodiment of the end effector2500 as shown in FIG. 31 with the clevis 2514 also shown. FIG. 33illustrates one embodiment of the clevis 2514. The clevis 2514 maycomprise a pair of arms 2554, 2556. Each arm 2554, 2556 may definerespective holes 2550, 2552 at the pivot point 2516, e.g., for receivinga pivot pin (not shown). As illustrated in FIG. 32, the shuttle 2520 mayride between the arms 2554, 2556. According to various embodiments, thearms 2554, 2556 may define recesses such as recess 2548 for receivingwire conduits (e.g., conduit 2542 shown in FIG. 25).

FIGS. 34 and 35 illustrate one embodiment of the jaw member 2502 of FIG.25. As shown, the jaw member 2502 may define a hole 2560 a at about thepivot point 2516. For example, the hole 2560 a may receive a pivot pin.The perspective shown in FIG. 35 provides a view of the slot 2534 b. Asurface 2662 b may partially or completely surround the slot 2534 b. Thesurface 2562 b may receive the flange 2528 a of the reciprocating member2524 as it translates distally. The flange 2528 a may exert a force onthe surface 2562 b, and therefore the jaw member 2502, (flange 2528 bmay exert a force on the surface 2562 a and therefore the jaw member2504), tending to cause the jaw members 2502, 2504 to the closedposition. At its proximal portion, the surface 2562 b may define anincline 2564 b for receiving the flange 2528 a. For example, the incline2564 b may allow the flange 2528 a to engage the slot 2534 b when thejaws 2502, 2504 are not in a closed or completely closed position. FIGS.36 and 37 illustrate one embodiment of the jaw member 2504 of FIG. 25.As illustrated, the jaw member 2504 may comprise a hole 2560 b, surface2562 a and incline 2564 a similar to those of the jaw member 2502described above.

Referring back to FIGS. 25 through 28, FIG. 25 shows the end effector2500 with the jaw members 2502, 2504 in an open position. In use, thejaw members 2502, 2504 may be placed around tissue, such as a bodilylumen to be severed and sealed. When the end effector 2500 is properlypositioned, the clinician may close the jaw members 2502, 2504 byoperating an actuator, such as 113, on the handle 102. This may causethe translating member 2530 to translate proximally, pulling the shuttle2520 proximally along with the cam pin 2518. This may pull the cam pin2518 proximally within the cam slots 2510, 2512, causing the jaw members2502, 2504 to pivot about the pivot point 2516 to the closed positionshown in FIG. 27. The clinician may then cause the reciprocating member2524 to extend distally (e.g., by using the actuator 113 or anotheractuator at the handle 102). This may cause the reciprocating member2524 to be received into the respective slots 2534 a, 2534 b. Flanges2528 a, 2528 b may contact surfaces 2562 a, 2562 b, exerting a force onthe jaw members 2502, 2504 tending to further close them, as shown inFIG. 28. The cutting edge 2526 of the reciprocating member 2524 maytransect tissue held within the jaws. According to various embodiments,the reciprocating member may be extended distally before the jaw members2502, 2504 are closed, or completely closed. For example, the flanges2528 a, 2528 b may engage the inclines 2564 a, 2564 b, exerting a forceon the jaw members 2502, 2504 tending to close them. In variousembodiments, severed tissue within the jaws 2502, 2504 may be sealed,for example, utilizing the electrical energy techniques describedherein. To open the jaw members 2502, 2504, the reciprocating member2524 may be withdrawn proximally from the slots 2534 a, 2534 b. Theshuttle 2520 may be pushed distally, for example, by exerting a distallydirected force on the translating member 2530 (e.g., via the handle102). Distal motion of the shuttle 2520 may cause the cam pin 2518 toslide distally within the cam slots 2510, 2512. This may, in turn forcethe jaw members 2502, 2504 to the open position. In various surgicalsituations, this may allow the clinician to dissect or separate tissuewith the instrument 100. Allowing the clinician to transect and seal aswell as dissect with the same instrument 100 may minimize the number ofinstrument changes required during an operation, thus reducing time andpotentially cost.

FIGS. 38-40 illustrate one embodiment of an end effector 2500′comprising an overtube 3802 for providing closing force to jaw members2502, 2504. As illustrated in FIGS. 25-26 and 38-39, the respective camportions 2508, 2510 of the jaw members 2502, 2504 may protrude away froma longitudinal axis 3806 of the end effector 2500′. As the jaw members2502, 2504 are closed, as shown in FIGS. 27-28 and 40, the cam portions2508, 2510 translate towards the axis 3806. According to variousembodiments, additional clamping force between the jaw members 2502,2504 may be obtained by forcing the cam portions 2508, 2510 towards theaxis 3806. This may be performed by an overtube 3802. The overtube 3802,like the reciprocating member 2524 and shuttle 2520 may be translatabledistally and proximally by the clinician from the handle 102. To closethe jaw members 2502, 2504, the shuttle 2520 may be translatedproximally, causing the jaw members 2502, 2504 to pivot towards the axis3806, as illustrated and described with reference to FIGS. 27-28.Overtube 3802 may then be translated distally, where it may contact thecam portions 2508, 2506, tending to force them and their respective jawmembers 2502, 2504 towards the longitudinal axis 3806. This may provideadditional clamping force tending to force the jaw members 2502, 2504together towards the longitudinal axis 3806. In some embodiments, theovertube 3802 may be shortened in length to more closely resemble a ringfor applications involving flexible shafts. This would be of particularbenefit for use in flexible endoscopic applications.

According to various embodiments, the shapes of the cam portions 2506and 2508 and/or the overtube 3802 may be optimized to reduce the forcenecessary to force the overtube 3802 distally and/or to increase thecompression force put on the jaw members 2502, 2504. For example, thecam portions 2506, 2508 may have curved sections 3810, 3812 positionedto contact the overtube 3802. The curved portions may be shaped to actas a camming surface to guide the overtube 3802 over the cam portions2506, 2508 and progressively increase the compressive force provided bythe overtube 3802 as it is translated distally. In some embodiments, theovertube 3802 may also comprise beveled camming surfaces 3808 around itsinterior distal edge to also guide the overtube 3802 over the camportions 2506, 2508 and progressively increase the compressive forceprovided by the overtube 3802 as it is translated distally. Also,according to various embodiments, it will be appreciated that the endeffector 2500′ may utilize a reciprocating member 2524 with flanges 2528a, 2528 b, as illustrated in FIGS. 29-31. The flanges 2528 a, 2528 b mayserve, as described, to provide additional compressive force as thereciprocating member 2524 is translated distally. In other variousembodiments, a reciprocating member 2520 may be used, as shown in FIG.39. The reciprocating member 2520 may comprise a sharp leading edge forsevering tissue, and may traverse within slots 2534 a, 2534 b of therespective jaw member 2502, 2504. The member 2520, however, may lackflange members, such as 2528 a, 2528 b. Accordingly, embodimentscomprising a reciprocating member such as the member 2520 may rely onthe cam portions 2508, 2506, cam slots 2512, 2510, and overtube 3802 toclose the jaw members 2502, 2504 and provide compressive force.

In various surgical settings, it may be desirable to close the jawmembers of an end effector without cutting tissue therebetween. In thisway, an end effector may be used as a grasper as well as adissecting/sealing instrument. FIGS. 41-43 illustrate one embodiment ofa reciprocating member 4140 that may be used in any of the end effectors106, 1200, 1500, 2000, 2300, 2500, 2500′ described above in order toallow closure of jaw members without the advancement of a blade. Themember 4140 may comprise an I-beam member 4102 and a blade member 4104positioned within the I-beam member. The I-beam member 4102 may comprisea transverse portion 4145 and a pair of flange portions 4144A, 4144B,for example, similar to those of reciprocating members described hereinabove. According to various embodiments, the I-beam member 4102 may alsodefine a recess 4106 beginning at its distal end. The blade member 4104may comprise a distally positioned leading edge or blade 4146. In use,the blade member 4104 and I-beam member 4102 may be separately slidablewithin the shaft 104 (not shown in FIG. 41). Each member 4104, 4102 maybe separately controllable from the handle 102. For example, each member4104, 4102 may be controllable from a separate motion of an actuator 113or actuators such as a trigger, a slide, etc.

To close an end effector, the I-beam member 4102 may be pushed distally.The flange portions 4144A, 4144B may act to close and compress jawmember portions, for example, as illustrated and described with respectto FIGS. 7-8, 15-18, 20, 22 and 23-24, etc. Because of the recess 4106,tissue or other material present between jaw members may not impededistal motion of the I-beam member 4102. If the clinician decides totransect tissue or other material present between the end effector's jawmembers, the clinician may cause the blade member 4104 to extenddistally to the position illustrated in FIG. 42 (e.g., by actuating ahandle 113 of the handle 102). The sharp leading edge 4146 (oralternatively a cutting electrode) of the blade member 4140 may transecttissue or other material as the blade member 4140 translates distally.According to various embodiments, the blade member 4104 and the I-beammember 4102 may be extended distally together, causing the reciprocatingmember 4140 to behave in a manner similar to the various reciprocatingmembers described above.

According to various embodiments, the end effectors 106, 1200, 1500,2000, 2300, 2500, 2500′ may be used to cut and fasten tissue utilizingelectrical energy. The examples described below are illustrated with theend effector 106. It will be appreciated, however, that similarconfigurations and techniques may be used with any of the end effectorsdescribed above. Referring to the end effector 106 shown in FIGS. 3-4and 7-8, the electrodes 120, 122 of the end effector 106 may be arrangedin any suitable configuration. In use, for example, tissue (not shown)may be captured between the jaw members 108, 110. RF current may flowacross the captured tissue between the opposing polarity electrodes 120,122. This may serve to join the tissue by coagulation, welding, etc. TheRF current may be activated according to any suitable control method.For example, according to various embodiments, the electrodes 120, 122may be used to implement a “power adjustment” approach, a “current-pathdirecting” approach or an approach referred to herein as a “weld” or“fusion” approach. These various approaches are illustrated herein withreference to FIGS. 44-47, which show the walls of an example bloodvessel acted upon by various RF end effectors including those using thepower adjustment and current-path directing approaches from above.

FIG. 44 shows an example embodiment of a vessel having opposing wallportions 2 a and 2 b. FIG. 45 is a graphic illustration of oneembodiment of the opposing vessel walls portions 2 a and 2 b with thetissue divided into a grid with arbitrary micron dimensions. Forexample, the grid may represent 5 microns on each side of the targetedtissue. In order to coagulate or weld tissue, collagen and other proteinmolecules within an engaged tissue volume may be denatured by breakingthe inter- and intra-molecular hydrogen bonds. When heat or other energyis removed (e.g., thermal relaxation), the molecules are re-crosslinkedto create a fused-together tissue mass. It is desirable that eachmicron-dimensioned volume of tissue be elevated to the temperatureneeded to denature the proteins therein in a substantially uniformmanner.

Failing to heat tissue portions in a uniform manner can lead to ohmicheating, which can create portions of tissue that are not effectivelyjoined and reduce the strength of the joint. Non-uniformly denaturedtissue volume may still be “coagulated” and can prevent blood flow insmall vasculature that contains little pressure. However, suchnon-uniformly denatured tissue may not create a seal with significantstrength, for example in 2 mm to 10 mm arteries that contain highpressures. It is often difficult to achieve substantially uniformheating with a bipolar RF device in tissue, whether the tissue is thinor thick. For example, as RF energy density in tissue increases, thetissue surface tends to become desiccated and resistant to additionalohmic heating. Localized tissue desiccation and charring can sometimesoccur almost instantly as tissue impedance rises, which then can resultin a non-uniform seal in the tissue. Also, many RF jaws cause furtherundesirable effects by propagating RF density laterally from the engagedtissue thus causing unwanted collateral thermal damage.

To achieve substantially uniform coagulation, various embodimentsdescribed herein may utilize a “power adjustment” approach, a“current-path directing” approach and/or an approach referred to hereinas a “weld” or “fusion” approach. According to the “power adjustment”approach, the RF generator 124 can rapidly adjust the level of totalpower delivered to the jaws' engagement surfaces in response to feedbackcircuitry, which may be present within the generator 124 and/or at theend effector 106, and may be electrically coupled to the activeelectrodes. The feedback circuitry may measure tissue impedance orelectrode temperature. For example, temperature probes present on thejaw members 109, 110, 1202, 1204 may be in communication with thegenerator 123 and may sense electrode temperature. FIG. 46 illustratesone embodiment of the blood vessel of FIG. 44 acted upon by a deviceimplementing a “power adjustment” approach to energy delivery. Opposingvessel walls 2 a and 2 b are shown compressed with cut-away phantomviews of opposing polarity electrodes 4602, 4604 on either side of thetissue. For example, the electrode 4602 may be positioned on one jawmember 108, 110, while the electrode 4604 may be positioned on theopposite jaw member. One advantage of such an electrode arrangement isthat 100% of each jaw engagement surface comprises an “active” conductorof electrical current—thus no tissue is engaged by an insulator whichtheoretically would cause a dead spot (no ohmic heating) proximate tothe insulator.

FIG. 46 also graphically depicts current paths p in the tissue at anarbitrary time interval that can be microseconds (μs) apart. Suchcurrent paths p would be random and constantly in flux—along transientmost conductive pathways through the tissue between the opposingpolarity electrodes. The thickness of the paths is intended to representthe constantly adjusting power levels. Typically, the duration of energydensity along any current path p is on the order of microseconds and thethermal relaxation time of tissue is on the order of milliseconds.Instruments using the power adjustment approach may be useful forsealing relatively small vessels with relatively low fluid pressure.This is because, given the spatial distribution of the current paths andthe dynamic adjustment of their power levels, it is unlikely that enoughrandom current paths will revisit and maintain each discretemicron-scale tissue volume at the targeted temperature before thermalrelaxation. Also, because the hydration of tissue is constantly reducedduring ohmic heating—any region of more desiccated tissue will lose itsohmic heating, rendering it unable to be “welded” to adjacent tissuevolumes.

In a second “current-path directing” approach, the end effector jawscarry an electrode arrangement in which opposing polarity electrodes arespaced apart by an insulator material, which may cause current to flowwithin an extended path through captured tissue rather than simplybetween surfaces of the first and second jaws. For example, electrodeconfigurations similar to those shown below in FIG. 47 may beimplemented on tissue engaging surfaces 350 a, 350 b, 1236 a, 1236 b.

“Current-path directing” techniques are also used to improve the qualityof energy-delivered seals. FIG. 47 illustrates one embodiment of theblood vessel of FIG. 44 acted upon by a device implementing acurrent-path directing approach to energy delivery. In FIG. 47, vesselwalls 2 a and 2 b are engaged between opposing jaws surfaces withcut-away phantom views of electrodes 4702, 4704, 4706, 4708, withopposing polarity (+) and (−) electrodes (4702, 4704 and 4706, 4708) oneach side of the engaged tissue. For example, electrodes 4702 and 4704may be positioned on one of the jaw members 108, 110, 1202, 1204 whileelectrodes 4706 and 4708 may be positioned on the opposite jaw member.An insulator 4710 is shown in cut-away view that electrically isolatesthe electrodes in the jaw. The tissue that directly contacts theinsulator 4710 will only be ohmically heated when a current path pextends through the tissue between the spaced apart electrodes. FIG. 47graphically depicts current paths p at any arbitrary time interval, forexample in the μs range. Again, such current paths p will be random andin constant flux along transient conductive pathways.

A third approach, according to various embodiments, may be referred toas a “weld” or “fusion” approach. The alternative terms of tissue“welding” and tissue “fusion” are used interchangeably herein todescribe thermal treatments of a targeted tissue volume that result in asubstantially uniform fused-together tissue mass, for example in weldingblood vessels that exhibit substantial burst strength immediatelypost-treatment. Such welds may be used in various surgical applicationsincluding, for example, (i) permanently sealing blood vessels in vesseltransection procedures; (ii) welding organ margins in resectionprocedures; (iii) welding other anatomic ducts or lumens where permanentclosure is desired; and also (iv) for performing vessel anastomosis,vessel closure or other procedures that join together anatomicstructures or portions thereof.

The welding or fusion of tissue as disclosed herein may be distinguishedfrom “coagulation”, “hemostasis” and other similar descriptive termsthat generally relate to the collapse and occlusion of blood flow withinsmall blood vessels or vascularized tissue. For example, any surfaceapplication of thermal energy can cause coagulation or hemostasis—butdoes not fall into the category of “welding” as the term is used herein.Such surface coagulation does not create a weld that provides anysubstantial strength in the treated tissue.

A “weld,” for example, may result from the thermally-induceddenaturation of collagen and other protein molecules in a targetedtissue volume to create a transient liquid or gel-like proteinaceousamalgam. A selected energy density may be provided in the targetedtissue to cause hydrothermal breakdown of intra- and intermolecularhydrogen crosslinks in collagen and other proteins. The denaturedamalgam is maintained at a selected level of hydration—withoutdesiccation—for a selected time interval, which may be very brief. Thetargeted tissue volume may be maintained under a selected very highlevel of mechanical compression to insure that the unwound strands ofthe denatured proteins are in close proximity to allow theirintertwining and entanglement. Upon thermal relaxation, the intermixedamalgam results in protein entanglement as re-crosslinking orrenaturation occurs to thereby cause a uniform fused-together mass.

To implement the welding described above, the electrodes 120, 122 (orelectrodes that are part of the other end effector embodiments describedherein) may, one or both, comprise an electrically conductive portion,such as copper or another suitable metal or alloy, and a portioncomprising a positive temperature coefficient (PTC) material having aselected increased resistance that differs at selected increasedtemperatures thereof. The PTC material may be positioned between theelectrically conductive portion and any tissue to be acted upon by theend effector 106. One type of PTC material is a ceramic that can beengineered to exhibit a selected positively slope curve oftemperature-resistance over a temperature range of about 37° C. to 100°C. Another type of PCT material may comprise a polymer having similarproperties. The region at the higher end of such a temperature rangebrackets a targeted “thermal treatment range” at which tissue can beeffectively welded. The selected resistance of the PTC matrix at theupper end of the temperature range may substantially terminate currentflow therethrough.

In operation, it can be understood that the electrodes 120 or 122 willapply active RF energy (ohmic heating within) to the engaged tissueuntil the point in time that the PTC matrix is heated to exceed themaximum of the thermal treatment range. Thereafter, RF current flow fromthe engagement surface will be lessened—depending on the relativesurface areas of the first and second electrodes 120, 122. This instantand automatic reduction of RF energy application may prevent anysubstantial dehydration of tissue proximate to the engagement plane. Bythus maintaining an optimal level of moisture around the engagementplane, the working end can more effectively apply energy to thetissue—and provide a weld thicker tissues with limited collateralthermal effects.

In various embodiments, surgical instruments utilizing variousembodiments of the transection and sealing instrument 100, with thevarious end effectors and actuating mechanisms described herein may beemployed in conjunction with a flexible endoscope. FIG. 48 illustratesone embodiment of an endoscope 4814 (illustrated here as a gastroscope)inserted into the upper gastrointestinal tract of a patient. Theendoscope 4814 may be any suitable endoscope including, for example, theGIF-100 model available from Olympus Corporation. The endoscope 4814 hasa distal end 4816 that may include various optical channels,illumination channels, and working channels. According to variousembodiments, the endoscope 4814 may be a flexible endoscope.

FIG. 49 illustrates one embodiment of a distal portion 4816 of theendoscope 4814, which may be used with the transection and sealinginstrument 100 described herein. The example endoscope 4814 showncomprises a distal face 4804, which defines the distal ends ofillumination channels 4808, an optical channel 4806 and a workingchannel 4810. The illumination channels 4808 may comprise one or moreoptical fibers or other suitable waveguides for directing light from aproximally positioned light source (not shown) to the surgical site. Theoptical channel 4806 may comprise one or more optical fibers or othersuitable waveguides for receiving and transmitting an image of thesurgical site proximally to a position where the image may be viewed bythe clinician operating the endoscope 4814. As described above, theworking channel 4810 may allow the clinician to introduce one or moresurgical tools to the surgical site. Examples of such surgical toolsinclude scissors, cautery knives, suturing devices, and dissectors. Itwill be appreciated that the endoscope 4814 is but one example of anendoscope that may be used in accordance with various embodiments.Endoscopes having alternate configurations of optical channels 4806,illumination channels 4808 and/or working channels 4810 may also beused. According to various embodiments, the endoscope 4814 may be, ormay be used in conjunction with, steerable devices such as traditionalflexible endoscopes or steerable overtubes as described in U.S. PatentApplication Publication No. 2010/0010299, incorporated herein byreference. Combinations of flexible endoscopes and steerable overtubesmay also be used in some embodiments.

In at least one such embodiment, the endoscope 4814, a laparoscope, or athoracoscope, for example, may be introduced into the patienttrans-anally through the colon, the abdomen via an incision or keyholeand a trocar, or trans-orally through the esophagus or transvaginallythrough the cervix, for example. These devices may assist the clinicianto guide and position the transection and sealing instrument 100 nearthe tissue treatment region to treat diseased tissue on organs such asthe liver, for example.

In one embodiment, Natural Orifice Translumenal Endoscopic Surgery(NOTES)™ techniques may be employed to introduce the endoscope 4814 andvarious instruments into the patient and carry out the variousprocedures described herein. A NOTES™ technique is a minimally invasivetherapeutic procedure that may be employed to treat diseased tissue orperform other therapeutic operations through a natural opening of thepatient without making incisions in the abdomen. A natural opening maybe the mouth, anus, and/or vagina. Medical implantable instruments maybe introduced into the patient to the target area via the naturalopening. In a NOTE™ technique, a clinician inserts a flexible endoscopeinto one or more natural openings of the patient to view the targetarea, for example, using a camera. During endoscopic surgery, theclinician inserts surgical devices through one or more lumens or workingchannels of the endoscope 4814 to perform various key surgicalactivities (KSA). These KSAs include forming an anastomosis betweenorgans, performing dissections, repairing ulcers and other wounds.Although the devices and methods described herein may be used withNOTES™ techniques, it will be appreciated that they may also be usedwith other surgical techniques including, for example, other endoscopictechniques, and laparoscopic techniques.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a clinician manipulating an end of aninstrument extending from the clinician to a surgical site (e.g.,through a trocar, through a natural orifice or through an open surgicalsite). The term “proximal” refers to the portion closest to theclinician, and the term “distal” refers to the portion located away fromthe clinician. It will be further appreciated that for conciseness andclarity, spatial terms such as “vertical,” “horizontal,” “up,” and“down” may be used herein with respect to the drawings. However,surgical instruments are used in many orientations and positions, andthese terms are not intended to be limiting and absolute.

While several embodiments have been illustrated and described, and whileseveral illustrative embodiments have been described in considerabledetail, the described embodiments are not intended to restrict or in anyway limit the scope of the appended claims to such detail. Additionaladvantages and modifications may readily appear to those skilled in theart. Those of ordinary skill in the art will readily appreciate thedifferent advantages provided by these various embodiments.

While several embodiments have been described, it should be apparent,however, that various modifications, alterations and adaptations tothose embodiments may occur to persons skilled in the art with theattainment of some or all of the advantages of the embodiments. Forexample, according to various embodiments, a single component may bereplaced by multiple components, and multiple components may be replacedby a single component, to perform a given function or functions. Thedescribed embodiments are therefore intended to cover all suchmodifications, alterations and adaptations without departing from thescope of the appended claims.

Various embodiments are directed to apparatuses, systems, and methodsfor the treatment of tissue. Numerous specific details are set forth toprovide a thorough understanding of the overall structure, function,manufacture, and use of the embodiments as described in thespecification and illustrated in the accompanying drawings. It will beunderstood by those skilled in the art, however, that the embodimentsmay be practiced without such specific details. In other instances,well-known operations, components, and elements have not been describedin detail so as not to obscure the embodiments described in thespecification. Those of ordinary skill in the art will understand thatthe embodiments described and illustrated herein are non-limitingexamples, and thus it can be appreciated that the specific structuraland functional details disclosed herein may be representative andillustrative. Variations and changes thereto may be made withoutdeparting from the scope of the claims.

Reference throughout the specification to “various embodiments,” “someembodiments,” “one embodiment,” or “an embodiment”, or the like, meansthat a particular feature, structure, or characteristic described inconnection with the embodiment is included in at least one embodiment.Thus, appearances of the phrases “in various embodiments,” “in someembodiments,” “in one embodiment,” or “in an embodiment”, or the like,in places throughout the specification are not necessarily all referringto the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments. Thus, the particular features, structures, orcharacteristics illustrated or described in connection with oneembodiment may be combined, in whole or in part, with the featuresstructures, or characteristics of one or more other embodiments withoutlimitation.

The entire disclosures of the following non-provisional United Statespatents are hereby incorporated by reference herein:

-   -   U.S. Pat. No. 7,381,209, entitled ELECTROSURGICAL INSTRUMENT;    -   U.S. Pat. No. 7,354,440, entitled ELECTROSURGICAL INSTRUMENT AND        METHOD OF USE;    -   U.S. Pat. No. 7,311,709, entitled ELECTROSURGICAL INSTRUMENT AND        METHOD OF USE;    -   U.S. Pat. No. 7,309,849, entitled POLYMER COMPOSITIONS        EXHIBITING A PTC PROPERTY AND METHODS OF FABRICATION;    -   U.S. Pat. No. 7,220,951, entitled SURGICAL SEALING SURFACES AND        METHODS OF USE;    -   U.S. Pat. No. 7,189,233, entitled ELECTROSURGICAL INSTRUMENT;    -   U.S. Pat. No. 7,186,253, entitled ELECTROSURGICAL JAW STRUCTURE        FOR CONTROLLED ENERGY DELIVERY;    -   U.S. Pat. No. 7,169,146, entitled ELECTROSURGICAL PROBE AND        METHOD OF USE;    -   U.S. Pat. No. 7,125,409, entitled ELECTROSURGICAL WORKING END        FOR CONTROLLED ENERGY DELIVERY;    -   U.S. Pat. No. 7,112,201, entitled ELECTROSURGICAL INSTRUMENT AND        METHOD OF USE;    -   U.S. Patent Application Publication No. 2010/0010299, entitled        ENDOSCOPIC TRANSLUMENAL ARTICULATABLE STEERABLE OVERTUBE; and    -   U.S. Patent Application Publication No. 2006/0111735, entitled        CLOSING ASSEMBLIES FOR CLAMPING DEVICE.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialdoes not conflict with existing definitions, statements or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

The devices disclosed herein may be designed to be disposed of after asingle use, or they may be designed to be used multiple times. In eithercase, however, the device may be reconditioned for reuse after at leastone use. Reconditioning may include a combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces, and subsequent reassembly. In particular, the devicemay be disassembled, and any number of particular pieces or parts of thedevice may be selectively replaced or removed in any combination. Uponcleaning and/or replacement of particular parts, the device may bereassembled for subsequent use either at a reconditioning facility, orby a surgical team immediately prior to a surgical procedure. Those ofordinary skill in the art will appreciate that the reconditioning of adevice may utilize a variety of different techniques for disassembly,cleaning/replacement, and reassembly. Use of such techniques, and theresulting reconditioned device, are all within the scope of thisapplication.

Preferably, the embodiments described herein will be processed beforesurgery. First a new or used instrument is obtained and, if necessary,cleaned. The instrument may then be sterilized. In one sterilizationtechnique, the instrument is placed in a closed and sealed container,such as a plastic or TYVEK® bag. The container and instrument are thenplaced in a field of radiation that may penetrate the container, such asgamma radiation, x-rays, or higher energy electrons. The radiation killsbacteria on the instrument and in the container. The sterilizedinstrument may then be stored in the sterile container. The sealedcontainer keeps the instrument sterile until it is opened in the medicalfacility.

The embodiments are not to be construed as limited to the particularembodiments disclosed. The embodiments are therefore to be regarded asillustrative rather than restrictive. Variations and changes may be madeby others without departing from the scope of the claims. Accordingly,it is expressly intended that all such equivalents, variations andchanges that fall within the scope of the claims be embraced thereby.

In summary, numerous benefits have been described which result fromemploying the embodiments described herein. The foregoing description ofthe one or more embodiments has been presented for purposes ofillustration and description. It is not intended to be exhaustive orlimiting to the precise form disclosed. Modifications or variations arepossible in light of the above teachings. The one or more embodimentswere chosen and described in order to illustrate principles andpractical applications to thereby enable one of ordinary skill in theart to utilize the various embodiments and with various modifications asare suited to the particular use contemplated. It is intended that theclaims submitted herewith define the overall scope.

1. A surgical instrument comprising: a handle; a shaft coupled to thehandle and extending distally along a longitudinal axis; an end effectorpositioned at a distal end of the shaft, wherein the end effectorcomprises: a first jaw member defining a first longitudinal slot; asecond jaw member defining a second longitudinal slot, the second jawmember pivotable towards the first jaw member about a pivot point andcomprising a cam pin positioned offset from the pivot point; and areciprocating member translatable distally and proximally parallel tothe longitudinal axis through the first longitudinal slot and the secondlongitudinal slot, wherein a distal portion of the reciprocating memberdefines a blade, and wherein the reciprocating member defines a cam slotfor receiving the cam pin, wherein distal motion of the reciprocatingmember exerts a force on the cam pin such that the second jaw memberpivots towards the first jaw member, and proximal motion of thereciprocating member exerts a force on the cam pin such that the secondjaw member pivots away from the first jaw member.
 2. The surgicalinstrument of claim 1, wherein the first jaw member is stationary andcoupled to the shaft.
 3. The surgical instrument of claim 1, wherein thefirst jaw member is also pivotable about the pivot point and comprises afirst jaw member cam pin, and wherein the reciprocating member alsodefines a second cam slot for receiving the first jaw member cam pinwherein distal motion of the reciprocating member exerts a force on thefirst jaw member cam pin such that the first jaw member pivots towardsthe second jaw member and proximal motion of the reciprocating memberexerts a force on the first jaw member cam pin such that the first jawmember pivots away from the first jaw member.
 4. The surgical instrumentof claim 1, wherein the pivot point is a rolling pivot point.
 5. Thesurgical instrument of claim 1, wherein the cam slot comprises a distalportion, a transition portion and a proximal portion.
 6. The surgicalinstrument of claim 1, wherein the reciprocating member comprises a pairof flanges positioned to ride above the first and second longitudinalslots when the reciprocating member is extended distally through thefirst and second longitudinal slots.
 7. The surgical instrument of claim1, wherein the first jaw member further comprises a first electrode andthe second jaw member further comprises a second electrode.
 8. Thesurgical instrument of claim 7 wherein at least one of the firstelectrode and the second electrode comprises a first electricallyconductive portion and a positive temperature coefficient (PTC) portion.9. The surgical instrument of claim 8, wherein the PTC portion comprisesat least one material selected from the group consisting of a polymerPTC material and a ceramic PTC material.
 10. The surgical instrument ofclaim 7, wherein the PTC portion comprises a PTC material with atemperature dependent electrical resistance such that the electricalresistance of the PTC material increases to substantially eliminatecurrent flowing through the PTC material at a predetermined temperature.11. The surgical instrument of claim 1, wherein the first jaw membercomprises a tissue engagement surface comprising a positive electrodeand a negative electrode separated by an insulator.
 12. A surgicalinstrument comprising: a handle; a shaft coupled to the handle andextending distally along a longitudinal axis; an end effector positionedat a distal end of the shaft, wherein the end effector comprises: afirst jaw member defining a first longitudinal slot, the first jawmember pivotable about a pivot point, and comprising first cam portionpositioned proximally from the pivot point; a second jaw member defininga second longitudinal slot, the second jaw member pivotable relative tothe first jaw member about the pivot point, and comprising a second camportion positioned proximally from the pivot point; a reciprocatingmember translatable distally and proximally parallel to the longitudinalaxis through the first longitudinal slot and the second longitudinalslot, wherein a distal portion of the reciprocating member defines ablade; and an overtube positioned over the shaft, wherein the overtubeis translatable distally toward the pivot point, wherein the overtube isconfigured to contact the first and second cam portions as it translatesdistally to apply a force on the first and second cam portions tendingto close the first and second jaw members.
 13. The surgical instrumentof claim 12, wherein an interior distal edge of the overtube defines abeveled edge.
 14. The surgical instrument of claim 12, wherein the firstand second cam portions define first and second interiorly positionedcam slots, further comprising: a shuttle translatable distally andproximally parallel to the longitudinal axis; and at least one cam pincoupled to the shuttle and positioned within the first cam slot and thesecond cam slot.
 15. The surgical instrument of claim 14, wherein thereciprocating member defines at least one slot and wherein the shuttleis positioned to translate within the slot distally and proximallyrelative to the reciprocating member.
 16. The surgical instrument ofclaim 14, wherein the at least one cam pin comprises a single cam pinpositioned to extend through the shuttle, the first cam slot and thesecond cam slot.
 17. The surgical instrument of claim 12, wherein thereciprocating member comprises a pair of flanges positioned to rideabove the first and second longitudinal slots when the reciprocatingmember is extended distally through the first and second longitudinalslots.
 18. The surgical instrument of claim 12, wherein the first jawmember further comprises a first electrode and the second jaw memberfurther comprises a second electrode.
 19. The surgical instrument ofclaim 18, wherein at least one of the first electrode and the secondelectrode comprises a first electrically conductive portion and apositive temperature coefficient (PTC) portion.
 20. The surgicalinstrument of claim 19, wherein the PTC portion comprises at least onematerial selected from the group consisting of a polymer PTC materialand a ceramic PTC material.
 21. The surgical instrument of claim 18,wherein the PTC portion comprises a PTC material with a temperaturedependent electrical resistance such that the electrical resistance ofthe PTC material increases to substantially eliminate current flowingthrough the PTC material at a predetermined temperature.
 22. Thesurgical instrument of claim 12, wherein the first jaw member comprisesa tissue engagement surface comprising a positive electrode and anegative electrode separated by an insulator.
 23. The surgicalinstrument of claim 12, further comprising a first translating membercoupled to the shuttle and extending proximally from the shuttle throughthe shaft to the handle.
 24. The surgical instrument of claim 12,wherein the reciprocating member extends proximally from through theshaft to the handle.
 25. The surgical instrument of claim 12, whereinthe end effector further comprises a clevis comprising a first arm and asecond arm, wherein the first arm and the second arm define holespositioned at about the pivot point.
 26. A surgical instrumentcomprising: a handle; a shaft coupled to the handle and extendingdistally along a longitudinal axis; an end effector positioned at adistal end of the shaft, wherein the end effector comprises: a first jawmember defining a first longitudinal slot; a second jaw member defininga second longitudinal slot, the second jaw member pivotable relative tothe first jaw member about the pivot point; and a reciprocating membercomprising: an I-beam member translatable distally and proximallyrelative to the longitudinal axis through the first longitudinal slotand the second longitudinal slot; a blade member translatable distallyand proximally separately from the I-beam member.
 27. The surgicalinstrument of claim 26, wherein the second jaw member comprises a campin positioned offset from the pivot point, and wherein the I-beammember defines a cam slot for receiving the cam pin, wherein distalmotion of the reciprocating member exerts a force on the cam pin suchthat the second jaw member pivots towards the first jaw member, andproximal motion of the reciprocating member exerts a force on the campin such that the second jaw member pivots away from the first jawmember.
 28. The surgical instrument of claim 27, wherein the first jawmember is also pivotable about the pivot point and comprises a first jawmember cam pin, and wherein the reciprocating member defines a secondcam slot for receiving the first jaw member cam pin wherein distalmotion of the reciprocating member exerts a force on the first jawmember cam pin such that the first jaw member pivots towards the secondjaw member and proximal motion of the reciprocating member exerts aforce on the first jaw member cam pin such that the first jaw memberpivots away from the first jaw member.
 29. The surgical instrument ofclaim 26, wherein the first jaw member comprises a first cam portionpositioned proximally from the pivot point, the second jaw membercomprises a second cam portion positioned proximally from the pivotpoint, and further comprising an overtube positioned over the shaft,wherein the overtube is translatable distally toward the pivot point,wherein the overtube is configured to contact the first and second camportions as it translates distally to apply a force on the first andsecond cam portions tending to close the first and second jaw members.30. The surgical instrument of claim 26, wherein the first jaw memberfurther comprises a first electrode and the second jaw member furthercomprises a second electrode.
 31. The surgical instrument of claim 30wherein at least one of the first electrode and the second electrodecomprises a first electrically conductive portion and a positivetemperature coefficient (PTC) portion.
 32. The surgical instrument ofclaim 31, wherein the PTC portion comprises at least one materialselected from the group consisting of a polymer PTC material and aceramic PTC material.
 33. The surgical instrument of claim 30, whereinthe PTC portion comprises a PTC material with a temperature dependentelectrical resistance such that the electrical resistance of the PTCmaterial increases to substantially eliminate current flowing throughthe PTC material at a predetermined temperature.
 34. The surgicalinstrument of claim 26, wherein the first jaw member comprises a tissueengagement surface comprising a positive electrode and a negativeelectrode separated by an insulator.